package luna.com.firefly.utils;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;

/**
 * 
 * <缩略图处理>
 * 
 * @author 陆小凤
 * @version [1.0, 2016年3月30日]
 */
public class ThumbnailGenerator
{
    
    public static void transform(String originalFile, String thumbnailFile, int thumbWidth, int thumbHeight, int quality)
        throws Exception
    {
        Image image = javax.imageio.ImageIO.read(new File(originalFile));
        
        double thumbRatio = (double)thumbWidth / (double)thumbHeight;
        int imageWidth = image.getWidth(null);
        int imageHeight = image.getHeight(null);
        double imageRatio = (double)imageWidth / (double)imageHeight;
        if (thumbRatio < imageRatio)
        {
            thumbHeight = (int)(thumbWidth / imageRatio);
        }
        else
        {
            thumbWidth = (int)(thumbHeight * imageRatio);
        }
        
        if (imageWidth < thumbWidth && imageHeight < thumbHeight)
        {
            thumbWidth = imageWidth;
            thumbHeight = imageHeight;
        }
        else if (imageWidth < thumbWidth)
            thumbWidth = imageWidth;
        else if (imageHeight < thumbHeight)
            thumbHeight = imageHeight;
        
        BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
        Graphics2D graphics2D = thumbImage.createGraphics();
        graphics2D.setBackground(Color.WHITE);
        graphics2D.setPaint(Color.WHITE);
        graphics2D.fillRect(0, 0, thumbWidth, thumbHeight);
        graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
        
        javax.imageio.ImageIO.write(thumbImage, "JPG", new File(thumbnailFile));
    }
}
